Shimrit - 3:48 pm on May 17, 2007 (gmt 0)
I used to be a professional forum moderator for some big sites in the UK. Our policy in cases like these varied from site to site according to what the site owners wanted, but generally it involved posting a reply to the suicide or suspected suicide threat, saying that you would like to help but are not qualified and giving the contact details for the Samaritans. If the threat seems immediate, then doing that and contacting the police seems to be the standard thing to do. One of our sites had a case like this and the site owners contacted the police, who contacted the police in that person's country and prevented the suicide. It sounds to me like you did exactly the right thing.